class User:
    def __init__(self,id,username,nickname,password):
        self.id = id
        self.username = username
        self.nickname = nickname
        self.password = password

class Classroom:
    def __init__(self,id,name,grade,major):
        self.id = id
        self.name = name
        self.grade = grade
        self.major = major

    def __str__(self):
        return f'{self.id}\t{self.name}\t{self.grade}\t{self.major}'